Abstract

Pollination by sonication is unusual in the Styphelioideae, family Ericaceae. Sprengelia incarnata andSprengelia propinqua have floral characteristics that suggested they might be adapted to buzz pollination. Both specieshave florally similar nectarless flowers except that the stamens of Sprengelia propinqua spread widely after the floweropens, while those of Sprengelia incarnata cohere in the centre of the flower. To test whether sonication occurs,we observed bee behaviour at the flowers of both plant species, documented potential pollinators, and examinedtheir floral and pollen attributes. We found that Sprengelia incarnata had smaller and drier pollen than Sprengeliapropinqua. We found that Sprengelia incarnata was sonicated by native bees in the families Apidae (Exoneura),Halictidae (Lasioglossum) and Colletidae (Leioproctus, Euryglossa). Sprengelia propinqua was also visited by beesfrom the Apidae (Exoneura) and Halictidae (Lasioglossum), but pollen was collected by scraping. The introduced Apismellifera (Apidae) foraged at Sprengelia propinqua but ignored Sprengelia incarnata. The two Sprengelia speciesshared some genera of potential pollinators, but appeared to have diverged enough in their floral and pollen characters to elicit different behaviours from the native and introduced bees.